Supernatural's spinoff will not be an "exact clone" of its parent series, according to one of the show's writers.

Andrew Dabb said that Supernatural: Bloodlines - which stars Lucien Laviscount as a rookie cop turned hunter caught in the crossfire of a monster war - will play out differently due to its city setting of Chicago.

"You don't want to do another show that's just about hunters, because then you're competing with Supernatural," Dabb told TVLine.

"It really was a conversation between myself, [series creator] Eric Kripke and [executive producers] Bob Singer and Jeremy Carver about what we can do to make it in the world of Supernatural, but not an exact clone of Supernatural.

"We got the idea that if you're in a city with 3 million people and you're a monster, you don't really need to leave. You can kill a lot of people and no-one would really notice.

"So if you stay, you're starting a family [and] then it could grow from there, and that led us to talk about the mob and five families."

Dabb also suggested that he would be keen to see Sam and Dean - the central characters in Supernatural - make further appearances on the spinoff beyond the backdoor pilot, which airs tonight (April 29) in the US.

He said: "Sam and Dean being here is really what starts Ennis, our hunter character, off and gets our monster families revved up.

"Sam and Dean being here is the first domino to fall that makes the series possible. It's incredibly important.

"They've got their own show to go to, and it's a great show. But should Bloodlines go forward, we'd love to have them back if things worked out scheduling-wise, and if we could find a story that's cool and doesn't feel like a repeat of the planted pilot."